Patient eye examinations may include a brief check of the pupil response and a retinal image. The typical eye examinations may be months apart and the actual examine a “snapshot” of the patient's eyes at a given moment and under fixed conditions at that moment. Pupil response may indicate a person's level of drowsiness and the person's ability to function normally for example safely drive a vehicle.
One in 10 motorists admits falling asleep behind the wheel. One in 10 drivers has fallen asleep while driving in the past 12 months, equating to 3.4 million motorists driving a total distance of more than 55,000 miles. So says LV=car insurance whose research has also revealed that these motorists drive at an average speed of 50 mph when they nod-off, in which time they cover an average distance of 26 meters—the equivalent of two double-decker buses. Official police figures, obtained via a Freedom of Information request, reveal that there were more than 3,357 fatigue-related road accidents recorded over the past five years. Yet only 15 police forces out of 51 were able to provide this information and so the actual figure is likely to be closer to 11,000, according to the firm. Of the 3.4 million motorists who confessed they had fallen asleep behind the wheel in the past 12 months, one in 20 (5%) say they had an accident and almost a third (29%) either swerved or veered off the road while dozing.
Many motorists admit they sometimes risk driving despite knowing they are too tired to safely operate a vehicle. Close to a third (28%) say they have got behind the wheel of their car while they were feeling drowsy and a fifth (19%) admit they've hardly been able to keep their eyes open while driving. The monotony of motorways and dual carriageways combined with a lack of sleep, are the main reasons cited for dozing while driving. Others blame long distance driving to get to a holiday destination, feeling tired after a late shift at work or feeling drowsy after taking medication. Typically drivers fall asleep behind the wheel at night when there is not much light and fewer cars on the road. Over half (56%) of those who fell asleep while driving say it happened between 8 pm and 6 am. The issue is particularly prevalent in male drivers, who are nearly three times as likely to fall asleep at the wheel than their female equivalents (33% of men compared to 12% of women).
A managing director of LV=car insurance, commented: The research shows that when people fall asleep behind the wheel it is usually because they are on a long monotonous road and haven't taken a break, or they haven't had enough sleep the night before. Falling asleep while driving, even momentarily, is extremely dangerous but taking regular breaks from driving can help prevent it. If you know you are going to be driving long distance, plan ahead and make sure you have sufficient time to rest.
It should be noted that various clinical conditions, especially neurological and ocular diseases, as well as numerous medications, may interfere with the measurements. Furthermore, a number of physiological parameters, such as the intensity of retinal illumination, the level of patient's alertness, the intensity of ambient light, as well as the time of day that the examination is performed may alter the obtained values.